As well as weekly hospital visits for treatment, when he was five, Ben also had to undergo surgery to insert a shunt after getting a build-up of fluid on the brain.

Dad Peter, 46, a speech therapist, said: “We try to live as normal a life as possible.

“We do have to think much more carefully about everything we do. With his sister Sarah you could notice the difference, we just did things, with Ben we have to think everything through.”

Ben’s illness means he has a different throat structure to most people and cannot be intubated, so any hospital treatment he needs must be given at Manchester, where the hospital staff have specialist skills.

Ben said: “We have to watch for my eye turning in. If my eye turns in it means I haven’t had enough to drink. Then I have to drink because if I don’t I’d get blue-lighted and I don’t want that because I might miss PE.”

Ben, who also lives with mum Tracey, 46, a chiropodist, and sister Sarah, 14, explains that PE is one of his favourite subjects at St Patrick’s Primary School, along with swimming and maths.

Peter added: “Ben’s very well because of the medication. We’ve been very lucky. The school is fantastic and his friends are all great with him.

“Even 15 years ago MPS would probably have killed him. There was a breakthrough with the drugs, and who knows, in 15 years there could be a cure.”

The family has helped raise funds toward that potential cure, as their local chemist, Norton Glebe Pharmacy, celebrated its first anniversary last month with events in aid of the Society for Mucopolysaccharide Diseases and Marie Curie Cancer Care.

Family member Keith Bilton began the fundraising by agreeing to have his beard - which he has sported for 40 years - shaved off.